Abstract
Some 78 species (23 grasses, 2 sedges. and 53 dicotyledons including 9 legumes) were seen to compose winter aspect growth of 14 grass-dominated communities of Karachi, Pakistan. The mean number of species per site was 10.71 ± 1.25 (range: 3 – 20, CV= 44.1%). Sixty-one species occurred in one or two sites only. Cenchrus setigerus, C pennisetiformis, Dichanthium. annulatum, Sporobolus arabicus, Cynodon dactylon and Tephrosia strigosa were relatively more frequently occurring species. Legumes were present invariably in all sites except Urochondra setulosa and Sporobolus havolus dominated communities. The number of species per site varied with the species dominating the site and the salinity status of the site. Halophytic communities were composed of lesser number of species as compared to the glycophytic communities. The aboveground standing phytomass (AGSP) varied from 37.6 g-2 for one of the Cyanodon dactylon community to 694.0 g-2 for Desmostachya bipinnata dominated site. Litter related with AGSP positively (r = + 0.5577; p < 0.01) as Litter (g-2 ) = 15.37 + 0.0657 AGSP (g-2) ± 18.96. Percent proportion of legumes biomass (PPLB) related inversely with proportion of grasses’ biomass (r = - 0.5757; p < 0.03) as PPLB = 39.483 – 0.4088 PPGB ± 7.362. The communities in hand, with respect to their AGSP, were found to have an order: D. bipinnata > U. setulosa > D. scindicum > S. arabicus > C. dactylon = S. halvolus > D. annulatum >C. pennisetiformis = C. aucherii = C. setigerus > S. verticillata. AGSP of waterlogged and semi-moist halophytic sites was substantially higher than that of dry glycophytic sites. The biomass distribution amongst the constituent species of each site was geometric. Edaphic characteristics of these communities have also been described.
